public class Example4_8 {
    public static void main(String args[]) {
      Circle circle = new Circle();            //[代码1]
      circle.setRadius(10);                    //[代码2]
      Circular circular = new Circular();      //[代码3]
      System.out.println("circle 的引用:"+circle);
      System.out.println("圆锥的bottom的引用:"+circular.bottom);
      circular.setHeight(5);
      circular.setBottom(circle);              //[代码4]
      System.out.println("circle的引用:"+circle);
      System.out.println("圆锥的bottom的引用:"+circular.bottom);
      System.out.println("圆锥的体积:"+circular.getVolme());
      System.out.println("修改circle的半径,bottom的半径同样变化");
      circle.setRadius(20);                    //[代码5]
      System.out.println("bottom的半径:"+circular.getBottomRadius());
      System.out.println("重新创建circle,circle的引用将发生变化");
      circle = new Circle();     //重新创建circle[代码6]
      System.out.println("circle 的引用:"+circle);
      System.out.println("但是不影响circular的bottom的引用");
      System.out.println("圆锥的bottom的引用:"+circular.bottom);
    }
}

